— i5 — 



Previous researches 1 ) had shown that thymene is a mixture of 

 p-cymene and an unknown terpene. In order to determine the nature 

 of this terpene it was split up into five fractions. As the b. p. in- 

 creased, so the rotation, density, and refraction diminished. We in- 

 vestigated more closely in particular the first, third, and fifth fractions. 

 Phellandrene (a and /?) could not be detected, although this substance 

 is a constituent of oil of ajowan herb 2 ). 



Of the first principal fraction we distilled 1,845 kilos (b. p. 165 

 to 180 ; di 5 o 0,8601; « D -f-8°4i / ; n D20° 1,48122). The bulk boiled 

 between 170 and 175 . As the b. p. rose the rotation diminished 

 more and more. In the fractions of which the b. p. was between 

 165 to 170 we were able to prove the presence of a-pinene by 

 means of the nitroso chloride (m. p. 103 to 104 ) and the nitrole 

 benzylamine (m. p.- 123 to 124 ). Shaking with dilute sulphuric acid 

 produced no hydrate; hydrochloric acid, or bromine yielded no solid 

 additive products. The principal ingredient of the fraction was p-cymene, 

 which was present in all the fractions of thymene. As always, we 

 proved its presence by oxidising with permanganate into hydrqxy-zso- 

 propyl benzoic acid, m. p. 155 to 15 6°; boiled with dilute hydro- 

 chloric acid it was converted into p-propenyl benzoic acid, m. p. 159 

 to 160 . 



The third principal fraction of the thymene showed the following 

 constants: di 5 o 0,8574, a D -\-Q° 24', n D20° M8345. The bulk of this 

 boiled between 179 and 181 . The rotation diminished with every 

 further fraction. From the fractions with the higher b. p. it was easy 

 to obtain a solid dihydrochloride possessing the characteristics of di- 

 pentene dihydrochloride (m. p. 48 to 49 ). The nitrosochloride, pre- 

 pared by the familiar process, had m. p. 104 to 105 ; the nitrole 

 piperidide melted at 152 to 153 . Here, therefore, we had to deal 

 with dipentene. The principal constituent was again p-cymene. 



The constants of the fifth principal fraction were as follow: 

 b. p. 179 to 181 , d 15 o 0,8547, a D _|_o 8', n D20 o 1,48054. This 

 fraction also yielded a dihydrochloride (m. p. 52 ) when hydrochloric 

 acid gas was passed into the solution in glacial acetic acid. The 

 fourth principal fraction yielded only liquid chlorides. The solid 

 chloride, however, was not identical with that possessing the m. p. 48 

 to 49 , for both chlorides, mixed in equal parts, melted when exposed 

 to the warmth of the hand. When hydrochloric acid was split off 

 from both chlorides by means of aniline, the hydrocarbon from the 

 dihydrochloride of m. p. 48 to 49 alone produced a well crys- 

 tallising tetrabromide (m. p. 123 to 124 ) which suffered no reduc- 



1 ) Comp. Gildemeister and Hoffmann, The Volatile Oils, p. 557. 

 2 j Report October 1903, 78. 



